The above kind of nut is known in prior art, for example, from Japanese Utility Model Publication No. 43-4602, Japanese Utility Model Publication No. 49-27159, Japanese Utility Model Public Disclosure No. 56-64801, Japanese Utility Model Public Disclosure No. 59-20020, and Japanese Utility Model Public Disclosure No. 63-42911.
The ornamental nut disclosed in Japanese Utility Model Publication No. 43-4602 includes a nut body having an annular groove in its upper portion. A spherical cap is fitted in the annular groove and secured therein. Desired characters or symbols are indicated on the inner surface of the cap by means of luminous paint, for example.
The ornamental nut disclosed in Japanese Utility Model Publication No. 49-27159 includes a head piece corresponding to the above-mentioned cap. The head piece is provided with a leg. The leg is threaded into the upper portion of the nut and secured therein.
The ornamental nut disclosed in Japanese Utility Model Public Disclosure No. 56-64801 includes a recess in the upper surface of the nut. A reflector plate of a hard material for reflecting light, such as a stainless plate or a chrome-plated steel plate, is placed on the bottom of the recess. A light-reflective body of a cap-like configuration formed from a transparent material is disposed on the reflector plate. The light-reflective body includes a hollow portion and an inner surface formed with irregularity. The light-reflective body is secured, at its periphery, in the recess in the upper surface of the nut by means of adhesive added with a fluorescent material, in order to reflect external light. Indicative ability is exerted by light from the fluorescent material.
The ornamental nut disclosed in Japanese Utility Model Public Disclosure No. 59-20020 includes a separate cap on the upper portion of the nut. The cap is crimped on the upper portion of the nut.
The ornamental nut disclosed in Japanese Utility Model Public Disclosure No. 63-42911 includes a semi-spherical cap fitted over the upper portion of the nut. The cap is formed from a transparent or translucent material. The inner surface of the cap is coated with a metal film, using a vacuum deposition technique. An engagement protrusion is formed around the fitted portion. The engagement protrusion is adapted to be securely engaged with an annular engagement groove formed in the inner peripheral surface of the upper portion of the nut.
In the nut of Japanese Utility Model Publication No. 43-4602, the cap is protruded outwardly, so that cracks, defects, breakage or dislodgement may occur easily, when subjected to a shock. In the nut of Japanese Utility Model Publication No. 49-27159, it is necessary to provide the leg on the head piece. It is also necessary for the leg to be formed with a threaded portion. Thus, manufacturing process is complicated and the production cost is increased. It is also noted that the threaded portion tends to be easily loosened and dislodged. Even when ornamental treatment is performed relative to the upper portion, scratches are easily caused. It is also noted that a solid and high-quality characteristic could not disadvantageously be given to the nut.
The nut of Japanese Utility Model Publication No. 56-64801 is of a construction in which a reflector plate of a hard material for reflecting light, such as a stainless plate or a chrome-plated steel plate, is placed on the bottom of the recess. The light-reflective body having a hollow portion is fitted over the reflector plate. The peripheries of the light-reflective body and the reflector plate are secured by means of adhesive. Thus, it is very difficult to evenly apply the adhesive, in order to prevent the adhesive from being protruding from the upper surface of the light-reflective body and the upper surface of the reflector plate. In this regard, the adhesive is preliminarily formed into an annular configuration. The thus formed ring is fitted around the reflector plate and then melt and adhered thereto by heating. This requires an extended period of time during manufacturing and assembling process. It is noted further that three parts are required, i.e., the reflector plate, the light-reflective body and the adhesive shaped into an annular configuration. This increases the cost for producing molds. Modification of design cannot be performed easily. Manufacturing process and assembling process are also complicated, thus increasing the production cost. It is also noted that the depth of the recess formed in the upper surface of the nut should be significantly increased, in order to preserve the hollow portion for the light-reflective body of a cap-like configuration. Thus, the length of the nut body is disadvantageously increased.
The nut of Japanese Utility Model Public Disclosure No. 59-20020 has a disadvantage in that the plating and coating of the nut body are damaged during crimping operation of the cap.
The nut of Japanese Utility Model Public Disclosure No. 63-42911 tends to easily cause cracks, defects and breakage when subjected to a shock, since the cap body is protruded outwardly. It is also noted that complicated and expense molds are required, since the nut includes the annular flange and the engagement protrusion. Furthermore, such nut cannot be easily manufactured.